Currently, Z—N catalyst is still the mainstream catalyst for olefins polymerization, Z—N catalyst for olefins polymerization, especially α-olefin polymerization, includes (1) titanium-containing magnesium chloride carrier catalyst component, (2) cocatalyst of organo-aluminum compound and (3) external electron donor for adjusting the poly-α-olefin's structure, wherein the titanium-containing magnesium chloride carrier catalyst component includes internal electron donor. In the present invention, the titanium-containing magnesium chloride carrier catalyst component shorts for catalyst component, there are two main methods for its preparation; one method is to firstly prepare magnesium chloride carrier, such as magnesium chloride-alcohols complex compound carrier, then carrying titanium and internal electron donor; the other method is directly reaction of magnesium chloride, alcohols, internal electron donor and titanium tetrachloride.
Internal electron donor plays a key role in regulating the activity of catalyst and poly-α-olefin's structure, and it is the core component of the catalyst component. However, the development of a practical internal electron donor is not easy, there are few internal electron donors that can be actually widely used which have limited performance, they cannot meet the growing demand for polyolefin industry. In recent years, it has been found that compound two or more kinds of electron donor as internal electron donor can get synergistic effect and obtain the performance different from single internal electron donor, which both have the advantages of two electron donors, and even produce new properties. The performance of the catalyst component, which compound two electron donors as internal electron donor, can be adjusted to get a catalyst component to meet the industrial demands. The preparation of catalyst component by compounding two electron donors as the internal electron donor is a new idea to develop a new catalyst component with excellent comprehensive performance or a certain excellent performance.
However, the preparation of catalyst component by compounding two electron donors as the internal electron donor is still in the experimental level by experiences, lack of rational methods to guide the research of internal electron donor compound catalyst component. It is not only unable to get the most desirable formula for preparing compound catalyst component and also causes the waste of internal electron donors. It is necessary to conduct a large amount of experiments to screen the good internal electron donor compounds, which may consume a lot of time, manpower and material resources.
To solve the above problems, the present invention establishes a method suitable to prepare catalyst component by compounding any two kinds of electron donors, and in particular discloses a method for preparing α-olefin polymerization catalyst component by compounding two electron donors as the internal electron donor, which is fast, accurate and practical.